The present invention is directed to a ferroelectric liquid crystal display apparatus and to a method for displaying an image using a back-lighted ferroelectric liquid crystal display panel.
A liquid crystal is an organic fluid which, despite being a fluid, has molecules which spontaneously assume an ordered configuration. This configuration can be altered by applying an electric field, and the resulting change in the configuration of the molecules can be used to control light passing through the liquid crystal. The liquid crystal is sandwiched between two polarizers having transparent electrodes made, for example, from metal oxide film. The polarization axis of light passing through the first polarizer is rotated by the liquid crystal if no voltage is applied between the electrodes, and the rotation disappears when a suitable voltage is applied. As a result, light passing through the first polarizer and the liquid crystal may or may not pass through the second polarizer, depending upon the applied voltage and hence the polarization axis of the light when it reaches the second polarizer.
A matrix of liquid crystal cells can be used in a liquid crystal display panel to display a sequence of frames of video information. A ferroelectric LCD panel has cells with very short turn-on and turn-off times. These cells are bistable; once a cell is turned on it remains on until it is turned off. One problem with prior art ferroelectric liquid crystal display apparatuses is that a satisfactory gray scale is difficult to achieve due to the bistable nature of the cells.